diff --git a/src/main/java/com/aidiary/domain/emotion/application/EmotionService.java b/src/main/java/com/aidiary/domain/emotion/application/EmotionService.java
index 4be5f0e..c1f1a99 100644
--- a/src/main/java/com/aidiary/domain/emotion/application/EmotionService.java
+++ b/src/main/java/com/aidiary/domain/emotion/application/EmotionService.java
@@ -2,6 +2,7 @@
 
 import com.aidiary.domain.diary.domain.Diary;
 import com.aidiary.domain.diary.domain.repository.DiaryRepository;
+import com.aidiary.domain.emotion.dto.DiaryEditEmotionRes;
 import com.aidiary.domain.emotion.dto.DiarysByEmotionRes;
 import com.aidiary.domain.emotion.dto.EmotionStatRes;
 import com.aidiary.domain.user.domain.User;
@@ -16,7 +17,6 @@
 import org.springframework.transaction.annotation.Transactional;
 
 import java.time.LocalDate;
-import java.util.List;
 
 @Service
 @RequiredArgsConstructor
@@ -76,4 +76,28 @@ public Slice<DiarysByEmotionRes> findDiarys(UserPrincipal userPrincipal, String
         Slice<DiarysByEmotionRes> allByEmotionAndUserId = diaryRepository.findAllByEmotionAndUserId(emotion, userPrincipal.getId(), pageable);
         return allByEmotionAndUserId;
     }
+
+    @Transactional
+    public DiaryEditEmotionRes editEmotion(Long userId, String emotion, Long diaryId) {
+        Diary diary = diaryRepository.findById(diaryId)
+                .orElseThrow(EntityNotFoundException::new);
+
+        if (!diary.getUser().getId().equals(userId)) {
+            return DiaryEditEmotionRes
+                    .builder()
+                    .diaryId(diaryId)
+                    .isEdited(false)
+                    .emotion(diary.getEmotion())
+                    .build();
+        }
+
+        diary.updateEmotion(emotion);
+
+        return DiaryEditEmotionRes
+                .builder()
+                .diaryId(diaryId)
+                .isEdited(true)
+                .emotion(emotion)
+                .build();
+    }
 }
diff --git a/src/main/java/com/aidiary/domain/emotion/dto/DiaryEditEmotionRes.java b/src/main/java/com/aidiary/domain/emotion/dto/DiaryEditEmotionRes.java
new file mode 100644
index 0000000..4a8cafb
--- /dev/null
+++ b/src/main/java/com/aidiary/domain/emotion/dto/DiaryEditEmotionRes.java
@@ -0,0 +1,11 @@
+package com.aidiary.domain.emotion.dto;
+
+import lombok.Builder;
+
+@Builder
+public record DiaryEditEmotionRes(
+        Long diaryId,
+        boolean isEdited,
+        String emotion
+) {
+}
diff --git a/src/main/java/com/aidiary/domain/emotion/presentation/EmotionController.java b/src/main/java/com/aidiary/domain/emotion/presentation/EmotionController.java
index 2122d7b..3cc46dc 100644
--- a/src/main/java/com/aidiary/domain/emotion/presentation/EmotionController.java
+++ b/src/main/java/com/aidiary/domain/emotion/presentation/EmotionController.java
@@ -108,4 +108,18 @@ public ResponseCustom<Slice<DiarysByEmotionRes>> findDiarysByEmotion(
     ) {
         return ResponseCustom.OK(emotionService.findDiarys(userPrincipal, emotion, pageable));
     }
+
+    @Operation(summary = "일기에 저장된 감정 수정", description = "일기에 저장된 감정을 수정합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "감정 수정 성공", content = {@Content(mediaType = "application/json", schema = @Schema(implementation = DiarysByEmotionRes.class))}),
+            @ApiResponse(responseCode = "400", description = "감정 수정 실패", content = {@Content(mediaType = "application/json", schema = @Schema(implementation = ErrorResponse.class))}),
+    })
+    @PatchMapping("{diaryId}/{emotion}")
+    public ResponseCustom<?> editDiaryEmotion(
+            @Parameter(description = "Accesstoken을 입력해주세요.", required = true) @CurrentUser UserPrincipal userPrincipal,
+            @Parameter(description = "수정할 감정(행복, 우울, 화남, 불안, 지루함)을 입력해주세요.", required = true) @PathVariable String emotion,
+            @Parameter(description = "감정을 수정할 일기의 id를 입력해주세요.", required = true) @PathVariable Long diaryId
+    ) {
+        return ResponseCustom.OK(emotionService.editEmotion(userPrincipal.getId(), emotion, diaryId));
+    }
 }